Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON):

Solution:
import collections
def f(mat):
	q,vis = collections.deque([((0,0), 1)]), set([(0,0)])
	while(q):
		u,d = q.popleft()
		if u == (len(mat)-1, len(mat[0])-1): return collections.Counter(reduce(lambda x,y:x+y, mat))['.'] - d
		for v in [(u[0]+1,u[1]), (u[0]-1,u[1]), (u[0],u[1]+1),(u[0],u[1]-1)]:
			if 0 <= v[0] < len(mat) and 0 <= v[1] < len(mat[0]) and (v not in vis) and mat[v[0]][v[1]] == '.':
				vis.add(v)
				q.append((v, d+1))
	return -1
print f([list(raw_input()) for l in range(map(int, raw_input().split())[0])])